Main Ring / Cooker Ring Trip RCD

[Scorpio80]

Hey everyone

help needed please.
Moved into a new home, and have just had all the first fit installed for a new kitchen. During first fit, the electrician changed a socket on the kitchen ring and then moved onto another part. Within a few minutes the whole house tripped on the RCD. He retraced steps and presumed he had nicked the cable in the new socket wiring so replaced wiring and tried again and the kitchen ring would hold for a minute and then trip all RCD. He tested the fault and identified that the neutral was having a problem.
Managed to fix the fault and had no issues. Now the second fit today, all going ok and all appliances work on the kitchen ring together, however as soon as the main rings are switched on, it trips the RCD. At the moment we can have all the kitchen on except the oven and main rings or kitchen and cooker and main rings cannot stay on.
He is finding it difficult to understand how the neutral holds the kitchen ring but won’t with the main ring.
Any ideas on potential issues.
Set up is island hob, extractor and separate oven and microwave oven.

thank you

 

[Dartlec]

Hey everyone

help needed please.
Moved into a new home, and have just had all the first fit installed for a new kitchen. During first fit, the electrician changed a socket on the kitchen ring and then moved onto another part. Within a few minutes the whole house tripped on the RCD. He retraced steps and presumed he had nicked the cable in the new socket wiring so replaced wiring and tried again and the kitchen ring would hold for a minute and then trip all RCD. He tested the fault and identified that the neutral was having a problem.
Managed to fix the fault and had no issues. Now the second fit today, all going ok and all appliances work on the kitchen ring together, however as soon as the main rings are switched on, it trips the RCD. At the moment we can have all the kitchen on except the oven and main rings or kitchen and cooker and main rings cannot stay on.
He is finding it difficult to understand how the neutral holds the kitchen ring but won’t with the main ring.
Any ideas on potential issues.
Set up is island hob, extractor and separate oven and microwave oven.

thank you

If the whole house tripped, I assume there's an RCD covering several circuits - does it cover the whole house, lighting etc too?

Hard to narrow the fault down too much without knowing what the 'fault' was he fixed.

It sounds like maybe there is too much 'leakage' from all circuits combined - that may be because the RCD is too sensitive (electrician should be able to test that).

So any individual circuit may not add up to enough to trip, but the combination of them is. Every appliance will 'leak' a small amount, so they can add up..

If that is the case, then adding an RCBO if possible for the new circuit might solve the problem.

The common theme from your description seems to be the oven, so worth PAT testing that perhaps. I've had a brand new microwave/oven that tripped the RCD after 30 seconds, even though it initially worked fine, PAT tested when cold fine, but clearly had an internal electronics issue.

 

[timhoward]

In very general terms I'd be IR testing circuits, ramp testing the RCD and seeing if removing loads changed the result, and/or measuring earth leakage with a sensitive clamp meter.

 

[Scorpio80]

Everything is completely brand new and yet to be used. Today was simply a second fit to get the power to appliances.

Rcd has main ring left, making ring right, garage, cooker, kitchen all on the same board. But youre right, one board with probably 5 circuits.

As said all appliances work on the kitchen ring, but the minute the mains left and right is flipped up, it trips the whole board.

 

[timhoward]

Any chance of a photo of the consumer unit - I think we'd understand you a bit more easily from that.

 

[Scorpio80]

So my understanding is that the cooker switch is the hob which is working, but the central heating is an old heating system we changed to a combo boiler which is now the oven main switch.
This switch remains in the on position of all others are on except the main rings.

 

[SJD]

If you are having substantial work done (sounds like you are) then I'd include changing that board for something more modern that better meets current regulations. There is one RCD that a fault on any circuit can trip, and often you've no idea which circuit has the issue. Get an all-RCBO board fitted, where each circuit has it's own RCB built into the circuit breaker - so a fault will trip only the one circuit.

 

[timhoward]

If you are having substantial work done (sounds like you are) then I'd include changing that board for something more modern that better meets current regulations

I was going to advise exactly the same thing. That board has done well and it's now fairly old. I believe it's an original MK Sentry board, and any parts would now only be available 2nd hand.

You said the "Cooker" is the Hob and "Immersion/Heating" is the Oven. At first glance that Oven you photographed is likely to require more than a 15A breaker. It might actually be the other way around.

 

[Strima]

Is this an actual electrician or a kitchen fitter who does wiring?

At the initial planning stage was any mention made of the consumer unit being upgraded?

without knowing what testing has been done and any test results it’s hard to say what is causing the problem.

I reflect the above comments that a full RCBO board would be a worthwhile investment.

 

[Scorpio80]

Fully qualified electrician and not a kitchen fitter.
Yes there was talk about a new board at the beginning but because of the additional circuits on the board not being used, it was suggested to use those instead.

 

[Scorpio80]

I was going to advise exactly the same thing. That board has done well and it's now fairly old. I believe it's an original MK Sentry board, and any parts would now only be available 2nd hand.

You said the "Cooker" is the Hob and "Immersion/Heating" is the Oven. At first glance that Oven you photographed is likely to require more than a 15A breaker. It might actually be the other way around.

Just tested hob with the board as shown in picture and it turns on so will check again why the cooker is on the 15A breaker. Thanks

 

[Scorpio80]

I was going to advise exactly the same thing. That board has done well and it's now fairly old. I believe it's an original MK Sentry board, and any parts would now only be available 2nd hand.

You said the "Cooker" is the Hob and "Immersion/Heating" is the Oven. At first glance that Oven you photographed is likely to require more than a 15A breaker. It might actually be the other way around.

Just checked specs on manual installation and picture below:

 

[timhoward]

Just checked specs on manual installation and picture below:

Pleased I'm wrong - these new oven's are quite efficient these days!